The present invention is directed to a remote adjustment mechanism for a louvered cleaning element of a combine harvester and in particular to an adjustment mechanism using two sensors for providing feedback to the operator of the louver position and for calibrating the adjustment mechanism.
Typically in a combine harvester, after threshing and separation, some chaff and straw are still mixed with the grain. The cleaning unit removes this trash from the grain. In most combines, the cleaning unit comprises three major components: a cleaning fan, a chaffer and a sieve. The cleaning fan has its own housing, whereas the chaffer and sieve are mounted to the cleaning shoe.
The cleaning fan is a multi-bladed fan located in front of the cleaning shoe. The air blast from the fan removes most of the chaff and straw from the grain by blowing the chaff and straw out the rear of the combine. The air blast can be regulated by adjusting fan speed or by changing the fan opening. The grain falls through the chaffer and sieve to a clean grain auger and is carried to the grain tank.
The cleaning shoe, which contains the chaffer and sieve, is mounted to the supporting structure of the combine, below the separating assembly. The bottom of the cleaning shoe contains the tailings auger and the clean grain auger.
The chaffer and sieve are suspended on hangers attached to the sides of the combine. There are three types of typical shoe action, reciprocating, shaking and cascading. In the reciprocating shoe, the chaffer and sieve move in opposite directions to one another. In the shaking shoe the chaffer and the sieve move in the same direction. In the cascading shoe the chaffer and sieve are arranged so that the material drops from one unit to another in a cascading or rolling motion.
Chaffers and sieves are either adjustable or non-adjustable. An adjustable chaffer or sieve is made up of one or more elements of transversely extending louvers with rows of teeth. Each of these louvers is mounted on a crankshaft having a crank arm that engages an axially extending adjusting bar. By axially moving the adjusting bar, all of the louvers are moved simultaneously to change the gap between adjacent louvers between fully opened and fully closed positions. Each element is typically adjusted separately though one actuator may be coupled to the adjusting bars of two or more elements.
The adjustable chaffer and sieve are adjusted in response to crop conditions. The louvers of the chaffer are opened or closed just enough so that the grain falls through the chaffer before passing the length of the chaffer. If the chaffer is opened too wide, it may overload the sieve with chaff. If the chaffer is not opened wide enough, grain will be lost out the rear of the combine. If the sieve is not opened wide enough, excess grain will be directed to the tailings auger. The louvers of the sieve must be opened far enough to allow kernels of grain to fall through easily, but not so far that straw and chaff are allowed to drop through. A combine harvester may be equipped with a pre-cleaner before the chaffer that includes yet another louvered cleaning element. As used herein, the term xe2x80x9ccleaning elementxe2x80x9d refers to any adjustable louvered element, whether in a pre-cleaner, chaffer or sieve.
With many combines, an operator must reach into the back of the combine between the sidesheets to adjust each element. This makes adjustment cumbersome and time consuming. Various remote adjustment mechanisms have been proposed. U.S. Pat. No. 4,897,072 discloses a cable drive mechanism that enables an operator to adjust the louver angle from the operator""s station. U.S. Pat. No. 5,586,033 discloses a device that adjusts the louver by a motor driven cable mechanism for automatic control. The motor is mounted to the combine frame. Other adjustment mechanisms use actuators mounted to the chaffer or sieve frame. These may be driven electrically. Each element may have its own actuator or a single actuator may be coupled to the adjusting bars of multiple elements within the chaffer and sieve.
A problem with using a cable drive to remotely adjust the cleaning element is the hysteresis due to cable windup and free play in the adjustment linkage joints. One solution for this hysteresis is to attach the actuator directly to the frame of the chaffer or sieve. The difficulty with attachment of the actuator to the frame is the vibration and shock loading of the actuator as the chaffer and sieve moves relative to the combine, in addition to free play in the linkage between the actuator and the adjusting bar. Another area of concern is proper feed back of the position of the louvers to the operator.
The present invention provides a compact actuator for each cleaning element of the combine harvester. The actuator has a linearly movable output member directly fastened to the adjusting bar of each element. The output member moves the adjusting bar to cause the opening of the louvers to be adjusted. The actuator includes an electrically driven motor to move the output member. Two non-contact sensors are used to determine the position of the output member. The motor and sensors are sealed within an actuator housing to protect these elements from dirt in the environment. A first sensor sends a signal to a microprocessor controller when the output member is in a home position. The home position of the output member corresponds to a known spacing of the louvers in the element. A second sensor sends a signal to the microprocessor that is responsive to movement of the output member. By tracking the movement of the output member from the home position, the current position of the output member is known, from which the opening of the louvers is determined based on the known geometry of the louvers.
An operator input device at a remote location includes switches, or other input mechanisms, to be used by the operator to activate the actuator. Multiple input devices can be used. An input device located in the operator""s cab allows the operator to make adjustments while harvesting. Another input device located on the side of the machine allows adjustments to be made to clean the elements or to make small adjustments when the machine is not harvesting.
Using non-contact sensors, preferably Hall effect sensors, improves the durability of the position feedback. With the output member directly coupled to the adjusting bar, backlash and hysteresis are largely eliminated from the system, enabling accurate feedback of the louver position to the operator without directly sensing the louver position with sensors in the crop and/or debris flow path.